The present invention relates to a signal processing system, and more particularly, to a signal processing system having an interface module into which a plurality of high-voltage functional blocks is integrated and each of the functional blocks is configured to perform a predetermined interface functionality.
For audio systems, such as DVD players or televisions, a digital-to-analog converter (DAC) in the audio system is usually configured to deliver signals of 2V Vrms (i.e. 5.65V Vpp), so a high supply power voltage such as 9V or 12V is required; however, it is impossible to integrate the whole DAC inside a system on chip (SOC) as the maximum power supply voltage is lower than 3.3V for sub micron processes. Therefore, stand-alone buffers are needed. In addition, there are usually multiple input signals for an analog-to-digital converter (ADC), so an M-to-1 multiplexer (MUX) is commonly needed for the ADC. If the whole M-to-1 MUX is integrated inside the SOC, the SOC has to supply 2*M pins for the M-to-1 MUX. For example, if the MUX integrated inside the SOC is a 7-to-1 MUX, the SOC needs to supply a total of 14 dedicated I/O pins. However, it is not preferable to integrate the whole ADC inside the SOC since pin counts are limited and precious. Therefore, a stand-alone MUX such as a low-THD MUX is needed.
Please refer to FIG. 1. FIG. 1 is an exemplary diagram illustrating a typical audio system 100. As shown in FIG. 1, the typical audio system includes an SOC 110, an audio codec 120, a stand-alone buffer 130, and a stand-alone MUX 140. The audio codec 120 is coupled to the SOC 110 via an I2S interface, and has a DAC 122 and an ADC 124 implemented therein. The stand-alone buffer 130 is coupled to the DAC 122, and the power supply voltage of the stand-alone buffer 130 is 9V or 12V rather than 3.3V supplied to the SOC 110 and the codec 120. As shown in FIG. 1, the stand-alone MUX 140 is coupled to the ADC 124 for outputting a selected input to the ADC 124. In this case where the components are implemented in the audio system individually without proper integration, the stand-alone components such as the buffer 130 and the MUX 140 cause an extra bill-of-material (BOM) cost and significantly increase the production cost.